Having dismantled the philosophy of the Same, Irigaray turns to reconstruction. Her 1984 work An Ethics of Sexual Difference opens with a provocation: "Sexual difference is one of the major philosophical issues, if not the issue, of our age." This is not a sociological observation. It is a claim about what genuine philosophy has yet to think.
For Irigaray, sexual difference does not mean the biological difference between male and female bodies, though it involves the body. It means something closer to a structural, ontological difference between two genuinely distinct modes of being a subject. She is not arguing that men and women are opposite types who balance each other out. She is arguing that Western culture has produced only one fully articulated subject position, the masculine, and that genuine sexual difference would require the creation of a second, genuinely feminine subject position that has never yet existed in its full form.
The key concept in her positive vision is the interval (l'entre-deux), the space between two different subjects. In genuine encounter between a man and a woman, or between any two sexually different subjects, what must be respected is the irreducibility of each to the other. The interval is not a gap to be overcome by fusion or sameness; it is the condition of real relation. Where there is only one type of subject, there can only be specular reflection, a man seeing himself mirrored, not genuine encounter with an other.
Irigaray's method of mimicry (mimétisme) is important here. Rather than directly asserting a female essence, she inhabits and displaces the texts of the tradition, speaking from within them, exaggerating their logic to the point where their exclusions become visible. The aim is not to replace one universal with another but to open a space where feminine subjectivity can begin to articulate itself.
Critics, including many feminists, have pushed back hard. Does Irigaray's emphasis on sexual difference reinscribe a binary that excludes queer, trans, and non-binary subjects? Does her vision of femininity rely on the very essentialism that has historically been used to oppress women? Irigaray's defenders argue that the interval model is more flexible than it appears: by insisting on an irreducible gap between subjects, it creates logical space for any number of positions that resist subsumption into a single universal. The debate remains live and productive.
Irigaray argues for an irreducible interval between masculine and feminine subjects, which would allow each sex to enter alliances with another sex and to remain as a specific sexuate subject for himself or for herself. An attentive reading of Irigaray also reveals the interval as a foundational threshold for queer and trans subjects in relation to themselves and in relationships with others.
— Contemporary commentary on Irigaray's concept of the interval, Sydney Review of Books (2024)